Top 10, 10th Class Heat...🎷

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10th Heat...🎷

* What is the difference between heat and temperature?
Heat is a form of energy. Heat energy is transferred by the hot object to a body at a lower temperature this energy of transfer is called heat.
Temperature is a quantitative major of the degree of hotness or coldness of a body. Temperature is expressed in °C, °F, or K (Kelvin).

* What are the different ways of heat transfer?
Ans. Conduction, convection and radiation are the ways of heat transfer.

In this lesson, we are going to study many definitions.

* Melting point
The temperature at which a solid converts into a liquid that particular temperature is called the melting point of that solid.
Ex. The melting point of gold is 1063 °C. 

* Boiling point
A particular temperature at which liquid converts into a gaseous state that temperature is called the boiling point of that liquid.
Ex. The boiling point of gold is 2700°C.

🎺 Explain the following temperature-time graph.

The above graph shows what happens when a mixture of ice and water is heated continuously.
a.  0,0:- temperature 0°C and time 0 minutes.
b.  AB:- the temperature of the mixture remains constant at 0°C till all the ice melts.
c.   BC:- temperature rises slowly from 0°C to 100°C as shown by the line BC.
d.  CD:- as water starts converting into steam from 0°C to 100 °C, further heat does not change the temperature.

* Evaporation
The conversion of liquid into a gaseous state below its boiling point process is called evaporation.
Evaporation takes place at any temperature.

* Specific Latent heat of fusion:- 
The amount of heat energy absorbed at constant temperature by the unit mass of a solid to convert into a liquid state is called the specific latent heat of fusion.

* Specific Latent heat of vaporization
The amount of heat energy absorbed at constant temperature by the unit mass of a liquid to convert into the gaseous state is called the specific latent heat of vaporization.

* Regelation

 The phenomenon in which the ice Converts to liquid due to applied pressure and then reconverts to ice once the pressure is removed is called resolution.
 As soon as the pressure is removed the melting point of ice is restored to 0°C, and again water gets converted into ice.

* Anomalous behavior of water

Generally, when heat is supplied to substances they get expanded, and cooled they get a contract. But water is an exception for a certain temperature. If water is cooled from 4°C to 0°C then it expands instead of contracts. The abnormal behaviour of water is called anomalous behavior.

At 4°C its volume is minimum. The density of water is maximum at 4°C.

* Humidity:- The presence of water vapor in the air makes it moist and the moisture of the atmosphere is called humidity.

* Due point temperature:-
Suppose unsaturated air at a certain temperature is taken and its temperature is decreased, a temperature is reached at which the air becomes saturated with water vapor. This temperature is called the dew point temperature.

* The vapor content in the air is measured using a physical quantity called absolute humidity.

* The mass of vapor present in a unit volume of air is called absolute humidity.

* The relative humidity:- the ratio of the actual mass of vapor content in the air for a given volume and temperature required to make the air saturated with water vapor at that temperature is called the relative humidity.

* The relative humidity at the dew point is 100%.

* If the relative humidity of the atmosphere is more than 60%, we feel that the air is humid.

* If the relative humidity of the atmosphere is less than 60%, we feel that the air is dry.

* The units of heat are Joule (J) in SI units and cal ( calorie ) in CGS units.

* 1 cal heat:- The amount of heat necessary to raise the temperature of 1 gm of water by 1°C from 14.5°C to 15.5 °C is called one calorie heat.

* 1 kcal heat:- The amount of heat necessary to raise the temperature of 1 kg of water by 1°C from 14.5°C to 15.5 °C is called one kcal heat.

1 kcal = 1000 cal.

🥁 Amazing fact
If we heat 1 kg of water by 1°C in a different temperature range than 14.5°C to 15.5 °C the amount of heat required will be slightly different.
  The relation between cal and joule
1 cal = 4.18 Joule.

* Specific heat:- the amount of heat energy required to raise the temperature of a unit mass of an object by 1 °C is called the specific heat of the object.
The specific heat capacity is denoted by the letter 'c'.

The SI unit of specific heat is J/Kg°C, and the CGS unit is cal/gm°C.

The specific heat capacity of water is 1 cal/gm°C, and the specific heat capacity of copper is 0.1 cal/gm°C.

* If the specific heat of an object is 'c', the mass of the object is 'm', and if the temperature of the object is raised by ∆ T °C, the heat energy absorbed by the objectives given by,
m × c × ∆ T

* Principal of heat exchange
Heat energy lost by the hot object = heat energy gained by the cold object.


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